Thermal decomposition of ammonium permanganate

The parent material, ammonium permanganate, was carefully decomposed in air at 120°. The product, referred to as the starting material (SM), was then subjected to thermal treatment in air for 5 hr in the temperature range 150–1200°. Chemical analysis of SM indicated that the main decomposition product of NH₄MnO₄ was Mn₂O₃, together with MnO₂, NH₄NO₃, H₂O and O₂. Mn₃O₄ started to form at 900°. The infrared spectra of various calcination products revealed the retention of NH ₄ ⁺ in the lattice structure up to 300°, and reflected the presence of excess oxygen as coordinated O ₂ ^– . The TG, DTA and IRA results on SM supported the chemical analysis data. X-ray analysis was carried out for phase identification and to follow transformations and the formation of a solid solution between MnO₂ and Mn₂O₃.

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Zusammenfassung Die Muttersubstanz, Aramoniumpermanganat, wurde in Luft bei 120° vorsichtig zersetzt. Das dabei erhaltene Ausgangsmaterial (SM) wurde danach in Luft 5 Stunden im Temperaturbereich von 150–1200° thermisch behandelt. Die chemische Analyse von SM ergab, daß als Hauptprodukt der Zersetzung von NH₄MnO₄, Mn₂O₃ auftritt neben MnO₂, NH₄NO₃, H₂O und O₂. Die Bildung von Mn₃O₄ beginnt bei 900°. Aus Infrarotspektren verschiedener Kalzinierungsprodukte ist ersichtlich, daß in der Gitterstruktur NH ₄ ⁺ bis 300° zurückgehalten wird und überschüssiger Sauerstoff in Form von koordiniertem O₂ vorliegt. Die Ergebnisse der TG-, DTA- und IRA-Untersuchungen von SM bestätigen Daten der chemischen Analyse. Mittels Röntgenanalyse wurden die Phasen identifiziert und der Verlauf der Phasenübergänge und der Bildung einer festen Lösung zwischen MnO₂ und Mn₂O₃ verfolgt.

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120°. , , 5 150–1200°. , , , , . 900° Mn₃O₄. 300° - O ₂ ^– . , . , .

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Paper presented at the World Conference on Thermal Analysis, Madeira (Portugal), 1986.     

Thermal decomposition of ammonium uranates

The thermal decomposition of ammonium uranates precipitated from uranyl nitrate solution on the addition of aqueous ammonium hydroxide and hexamine under various conditions has been studied by means of thermogravimetry, differential thermal analysis, infrared spectroscopy and X-ray diffraction. Although all precipitates show the composition corresponding to UO₃ · NH₃ · H₂O, the precipitates with hexamine give X-ray diffraction patterns designed as types I and II, in which type I is similar to the precipitates with ammonia. As a result, it is concluded that ammonium uranates thermally decompose to amorphous UO₃ at about 400°, and transform to U₃O₈ via-UO₃ and/or-UO₃, latter being formed in the case of type II only.

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Zusammenfassung Die thermische Zersetzung von unter verschiedenen Bedingungen durch wässrige Lösungen von Ammoniumhydroxid und Hexamin aus Uranylnitrat-Lösung gefällten Ammoniumuranaten wurde mittels TG, DTA, IR-Spektroskopie und Röntgendiffraktometrie untersucht. Obwohl die Zusammensetzung aller Niederschläge der Formel UO₃ · NH₃ · H₂O entspricht, geben die mit Hexamin gefällten Niederschläge die als Typ I und II bezeichneten Röntgendiffraktogramme, von denen das des Typs I ähnlich dem der mit Ammoniak gefällten Niederschlage ist. Es wird festgestellt, daß Ammoniumuranate bei 400° thermisch zu amorphen UO₃ zersetzt werden und sich über-UO₃ und/oder-UO₃—wobei beim Typ II nur das letztere gebildet wird — in U₃O₈ umwandeln.

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, , - - , . @2 UO₃ · NH₃ · H₂O, , - I II. . , 400° UO₃ U₃O₈ -UO₃ -UO₃. II.

     

Thermal decomposition of ammonium perchlorate

This review represents an attempt to summarize literature data on thermal decomposition of ammonium perchlorate. The mechanism of thermal decomposition and various factors which influence on the thermal decomposition of ammonium perchlorate are discussed.     

Thermal decomposition of ammonium metavanadate

Ammonium metavanadate is subjected to thermal treatment in the range 180–550°C and structural and surface area changes are studied by X-ray diffraction and N₂ adsorption. DTA and TGA show the existence of a large endotherm (260°C) possibly composed of several stages, and a much smaller one (340°C) which is responsible for evolution of the molecule of water associated with the V₂O₅ initially formed. Three exotherms also appear and explanations for their presence are given. The phases formed, as well as the specific surface areas, are determined for the products obtained in a vacuum and in the presence of water vapour, and changes in surface areas are related to the phase transformations and dehydration of the products formed during thermal treatment.     

Thermal decomposition of ammonium uranium fluoride

Thermal decomposition of uranium double fluoride in a screw reactor in the temperature range of 250–500 °C is presented. Using integral reactor relation, kinetic parameters are discussed in terms of the shrinking core grain model. Arrhenius global activation energy is also determined.     

Thermal decomposition of ammonium cerous carbonate

The thermal decomposition of ammonium ceryl(III) carbonate (ACeC) [NH₄CeO(CO₃)] was investigated by thermogravimetry, differential thermal analysis and X-ray diffraction. The results showed three endothermic stages of decomposition, each involving a loss in weight. The first stage, at 65.5 °C, is characteristic of the removal of adsorbed water, the second stage, at 214.8 °C, is associated with ammonia release, and the third stage, at 263.6 °C, relates to the removal of carbon dioxide.     

Thermal decomposition of tetraethyl ammonium tetrafluoroborate

Thermal decomposition of tetraethyl ammonium tetrafluoroborate has been studied employing simultaneous techniques of TG–DTG–DSC—quadrupole mass spectrometric techniques in an inert atmosphere of pure Helium gas at a sample heating rate of 5 K min^?1 employing a platinum crucible. The observed decomposition paths are the most commonly expected Hofmann elimination and substitution reactions paths.     

Thermal decomposition of doped ammonium perchlorate

Isothermal decomposition of orthorhombic ammonium perchlorate (AP) has been studied as a function of concentration of the dopants, SO ₄ ^2– and PO ₄ ^3– . In either case, the rate of decomposition passes through a maximum as the dopant concentration increases. Activation energy of the decomposition process remains unaltered by doping. The results are interpreted in terms of electron transfer mechanism.

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Zusammenfassung Die isotherme Zersetzung von orthorhombischen Ammoniumperchlorat (AP) wurde in Abhängigkeit von der Konzentration der Dopanten SO ₄ ^2– und PO ₄ ^3– untersucht. In jedem Falle geht die Geschwindigkeit der Zersetzung mit steigender Dopantenkonzentration durch ein Maximum. Die Aktivierungsenergie des Zersetzungsprozesses wird durch dopen nicht verändert. Die Ergebnisse werden auf einem Elektronentransfer-Mechanismus basierend interpretiert.

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The author is thankful to Dr. V. R. Pai Verneker of Indian Institute of Science, Bangalore, for stimulating discussions.     

Thermal decomposition of ammonium monochloroacetate and ammonium monochloroacetate silicomolybdate

Journal of Thermal Analysis and Calorimetry - Les anomalies que nous avons observées, dans le cas de l'oxydation de fils de nickel, peuvent s'interpréter en faisant appel à...     

Thermal decomposition of ammonium perchlorate single crystals

The thermal decomposition of large single crystals of pure ammonium perchlorate and ammonium perchlorate doped with Ba2⁺ or SO^2?₄ ions has been investigated over the temperature range 220–290°C. Comparative studies were also made with compressed pellets of the pure powder and with small single crystals containing macroscopic flaws. The kinetic results were analyzed using a computer technique which permits a very detailed examination of various kinetic models. This reveals that the “induction period” (α < ～ 0.01) is very complex and comprises a desorption step, a linear process, an exponential process, and the beginnings of an Avrami process. The latter three processes are identified with (i) the inward growth of rapidly formed surface nuclei, (ii) “branching” of surface nuclei, and (iii) nucleation in the bulk crystal. Kinetic parameters are obtained for these three processes and also for the growth of nuclei in the bulk crystal. This model fits the kinetic data over the complete range of α(0–1), or 1 × 10^?5 < α < 1 if the desorption step is not included. The mechanism of the reaction and possible effects on this of Ba²⁺ and SO^2?₄ doping are discussed briefly.     

Thermal decomposition of ammonium fluoromanganates(III)

The thermal decomposition of ammonium fluoromanganates (III) has been investigated in air and argon by simultaneous thermogravimetry and differential thermal analysis. Chemical analysis, X-ray powder data, and infrared spectra have been employed to characterise the intermediate and final products. The thermal decomposition can be described by the sequence (NH₄₃MnF₆ → (NH₄)₂MnF₅ → NH₄MnF₄ → MnF₂. Although penta- and tetra-fluoromanganates are well-defined compounds, the intermediate states could not be separated. In addition, a high temperature form of ammonium hexafluoromanganate has been observed.     

Thermal decomposition of ammonium nitrate with three-component additives

Results of a thermal analysis of a system constituted by ammonium nitrate and a three-component additive with Mg(NO₃)₂ as a promising ecologically clean oxidizing agent for high-energy condensed systems are presented.     

Thermal decomposition of ammonium perchlorate based mixture with fullerenes

The effects of fullerenes, including fellerene soot (FS), extracted fullerene soot (EFS) and pure C₆₀ on the thermal decomposition of ammonium perchlorate (AP) compared with traditional carbon black (CB) catalyst has been studied by employing thermogravimetry (TG), differential thermal analysis (DTA), infrared spectroscopy (IR) and ignition temperature experiments. The results showed that the addition of CB and FS to AP reduced the activation energy as well as the temperature at maximum decomposition rate, but that of EFS and pure C₆₀ had little effect on the thermal decomposition of AP, and among all catalysts, FS was the best one.     

Thermal decomposition properties of double-base propellant and ammonium perchlorate

The thermal decomposition properties and the heat of combustion (ΔH) of samples with different ammonium perchlorate (AP)/double base propellant (DB) mass ratios under argon atmosphere were studied by the thermogravimetry–differential scanning calorimetry–mass spectrometry–Fourier transform infrared spectroscopy (TG–DSC–MS–FTIR) and automatic calorimeter method. The results show that decomposition process of AP/DB samples in negative and zero oxygen balance (OB) is different from that in positive OB. With the increasing of AP in the AP/DB samples, the decomposition of the samples becomes more and more severe. When the OB of the samples is positive, the phenomenon of deflagration or explosion could be observed in the decomposition process. The sample with OB = 0 has the greatest heat of combustion.     

Thermal decomposition of ammonium uranates precipitated from uranyl nitrate solution with ammonium hydroxide

Thermal decomposition of ammonium uranates precipitated from uranyl nitrate solutions on addition of aqueous ammonium hydroxide under various conditions has been examined by thermogravimetry (TG), differential thermal analysis (DTA), infrared spectroscopy and X-ray diffraction study. The TG curves of all precipitates show the weight-loss corresponding to the calculated value as UO₃·NH₃·H₂O. The DTA curves of the precipitates give the endotherms at about 130, 210 and 590 °C and the exotherms at 340–420 °C. As a result, it is found that ammonium uranates thermally decompose to amorphous UO₃ at about 400 °C, and transform to U₃O₈ via β-UO₃.     

Thermal decomposition of the high-performance oxidizer ammonium dinitramide under pressure

Ammonium dinitramide (ADN) is a promising new oxidizer for solid propellants because it possesses both high oxygen balance and high energy content, and does not contain halogen atoms. A necessary characteristic of solid propellants is chemical stability under various conditions. This study focused on the thermal decomposition mechanism of ADN under pressurized conditions. The pressure was adjusted from 0.1 to 6 MPa, while ADN was heated at a constant rate. The exothermal behavior and the decomposition products in the condensed phase during heating were measured simultaneously using pressure differential scanning calorimetry (PDSC) and Raman spectrometry. PDSC analyses showed the multiple stages of exotherms after melting. The exothermal behavior at low temperatures varied with pressure. Analysis of the decomposition products indicated that ammonium nitrate (AN) was generated during decomposition of ADN at all pressures. At normal pressure, AN was produced at the same time as start of exotherm. However, the temperature at which the ratio of ADN in chemical species in the condensed phase began to decrease under high pressure was higher than that at atmospheric pressure despite the existence of significant exotherm. At initial stage, thermal decomposition of ADN that does not generate AN was thought to be promoted by increased pressure.